MiR-203a-3p in extracellular vesicles derived from mesenchymal stem cells alleviates BPD-associated apoptosis and inflammation

Background: Bronchopulmonary dysplasia (BPD) is the most well-known disease contributing to mortality and long-term morbidity in premature infants. Although the pathogenesis of BPD is multifactorial, hyperoxia-induced lung injury and inflammation are recognized as major causes of BPD. Extracellular vesicles (EV) are known to function as a powerful cell-cell communicator by delivering their cargo including proteins, lipids, and nucleic acids such as microRNAs. EVs derived from mesenchymal stem cells (MSC) are recently reported as promising and effective therapeutic modalities for BPD. Methods: The therapeutic effects of MSC-derived EV were examined using a BPD animal model. Differentially expressed miRNAs were selected through miRNA sequencing. The regulation of target genes by miRNA was investigated by Western blot, RT-qPCR, Ago2 RNA immunoprecipitation, and luciferase reporter assay. The increase in therapeutic efficacy of EVs by miRNA was demonstrated by confirming the anti-apoptotic and anti-inflammatory effects of EVs secreted by HEK293 cells overexpressing miR-203a-3p. Results: Through an in vivo BPD animal model, MSC-derived EVs exhibited protective effects against hyperoxia-induced lung injuries. To define the molecular mechanisms by which MSC-derived EVs alleviate BPD, anti-apoptotic and anti-inflammatory effects were examined. MicroRNA-203a-3p (miR-203a-3p) present in MSC-derived EVs exhibited inhibitory effects on H₂O₂-induced apoptotic cell death by targeting inhibitor of differentiation 4, as well as on lipopolysaccharide-induced inflammatory cytokine expression by targeting myeloid differentiation primary response 88. Experiments with miR-203a-3p inhibitor revealed that miR-203a-3p was responsible for mitigative effects of MSC-derived EVs. Compared to EVs containing control mimic, EVs containing miR-203a-3p mimic exhibited higher anti-apoptotic and anti-inflammatory effects. Conclusions: Our findings revealed that miR-203a-3p in MSC-derived EVs inhibited apoptotic cell death and inflammation, demonstrating that miR-203a-3p is a key player enabling MSC-derived EVs to exhibit therapeutic effects for BPD.